Seismic and Structural Health Monitoring of Large Concrete Dams

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Numerical models for seismic analysis of arch dams

Publication . Alegre, André; Oliveira, Sérgio; MENDES, PAULO; Proença, Jorge; Carvalho, Ezequiel; Matsinhe, Bruno

This paper presents a study on the seismic behaviour of large arch dams under strong earthquakes. The numerical simulations are carried out using DamDySSA, a 3D finite element program developed for dynamic analysis of concrete dams, which includes calculation modules for linear seismic analysis and for non-linear seismic analysis, considering the effects of joint movements and tensile and compressive damage in concrete. The case studies are the 132 m-high Cabril dam, in Portugal, and the 170 m high Cahora Bassa dam, in Mozambique. The seismic response results computed using linear and non-linear models are compared, in order to investigate the influence of the joint movements on the structural response, and to analyse the resulting concrete damage under a strong seismic load. Overall, there was a release of arch stresses in the upper part of both dams, due to the opening of the vertical joints, and consequently an increase of vertical stresses along the main cantilevers, causing concrete tensile failure. Furthermore, this study emphasized the potential of the developed numerical methods and thus of DamDySSA for predicting the non-linear seismic behaviour of arch dams.

2022-09Conference object

Open access

Seismic safety assessment of arch dams using an ETA-based method with control of tensile and compressive damage

Publication . Alegre, André; Oliveira, Sérgio; MENDES, PAULO; Proença, Jorge; Ramos, Rafael; Carvalho, Ezequiel

The seismic safety assessment of large concrete dams remains a significant challenge in dam engineering, as it requires appropriate analysis methods, modern performance criteria, and advanced numerical models to simulate the dam seismic behavior. This paper presents a method for seismic safety assessment of arch dams based on Endurance Time Analysis (ETA), using tensile and compressive damage results from a robust formulation for seismic analysis considering joint opening/sliding and concrete non-linear behavior (finite element program DamDySSA, under development in LNEC). The seismic performance is evaluated by controlling the evolution of the damage state of the dam, according to predefined performance criteria, to estimate acceleration endurance limits for tensile and compressive damage. These acceleration limits are compared, respectively, with the peak ground accelerations prescribed for the Operating Basis Earthquake (OBE) and Safety Evaluation Earthquake (SEE), aiming to evaluate the dam seismic performance relative to both earthquake levels efficiently, using a single intensifying acceleration time history. The ETA-based method is applied to the cases of Cabril Dam (132 m-high) and Cahora Bassa Dam (170 m-high), confirming its usefulness for future seismic safety studies, while the potential of DamDySSA for non-linear seismic analysis of arch dams is highlighted.

2022-11-25Journal article

Open access